DNA-binding property of free and chromatin-bound RNA polymerase II. Analysis by DNA-Sephadex G-25 chromatography

Differential changes of tightly chromatin-bound RNA polymerase II in starved and cycloheximide-treated rat liver nuclei

In order to investigate the physiological function of loosely and tightly chromatin-bound RNA polymerase II in vivo (1), the changes of these enzyme activities in cycloheximide-treated or starved rat liver nuclei were studied. Total nuclear mRNA synthesis activity in starved rats was considerably decreased, but that of cycloheximide-treated rats was not affected significantly. In starved rats, tightly bound enzyme activity was much more repressed as compared with that of loosely bound enzyme. On the other hand, cycloheximide-treated rats showed the reverse relationship. Thus, mRNA synthesis activity in hepatic nuclei seems to be dependent on the tightly bound RNA polymerase II activity. However, the difference of nuclear mRNA synthesis in both cases can not be explained by the change of chromatin-bound enzyme activity of Yu (2).

A decrease of RNA synthesis during macrophage activation with lipopolysaccharide--an association with novel regulating factors

RNA synthesis during macrophage activation with lipopolysaccharide (LPS) was analyzed in mice. The RNA synthesis of macrophages was considerably increased early after LPS stimulation, but drastically decreased at a later period. The decrease of RNA synthesis was observed in mouse strains responding to LPS such as BALB/c, ATL and ddY, but not in nonresponder strain, C3H/HeJ. Furthermore, the decrease of RNA synthesis occurred in both alpha-amanitin resistant and sensitive RNA polymerase reactions. However, RNA polymerases in nuclei were not changed significantly in LPS-treated macrophages, but the factors affecting RNA polymerase reactions were drastically changed. Amongst these factors, the stimulating factors were decreased and a novel repressing factor was remarkably increased. The factors were partially characterized and their significance in macrophage activation is discussed.